Kp-Index — The Storm Strength Meter — Aurora Guide

Kp-Index — The Storm Strength Meter

The Kp-index is a number from 0 to 9 that measures how much Earth's magnetic field is being disturbed. Think of it as a storm intensity meter for auroras — the higher the number, the further south you can see them.

Storm Intensity 0 → 9
0123456789
Kp 0–2QuietOnly inside the Arctic Circle (Tromsø, Svalbard)
Kp 3–4ActiveNorthern Canada, Alaska, Iceland, Scandinavia
Kp 5–6Minor stormNorthern Scotland, southern Norway, Estonia, northern US & Canada
Kp 7–8Strong stormEngland, Germany, Poland, Chicago, Toronto
Kp 9Severe stormRare! France, Italy, Japan, Texas — the 1859 Carrington Event!
Use both together: Kp tells you how strong the disturbance is and how far south the aurora reaches. Bz tells you how bright and active it will be. A Kp 4 with Bz –15 nT will put on a far better show than a Kp 4 with Bz +2 nT.
Continue Reading
←Bz — The Aurora Intensity DialWhy Different Colours?→
📖 Explore the full aurora guide
Check tonight's aurora forecast
🇳🇴Tromsø→🇮🇸Reykjavík→🇺🇸Fairbanks→🇫🇮Rovaniemi→
Dark
Menu